Photographic lens system.



l. 0R 73 Draftsman! i No. 730,937. V" I K PATENTEDfiINEiB, 190.3. I

-- E. LOHMANN. PHOTOGRAPHIO LENS SYSTEM.

APPLIQATIOI FILED 10V. 8, 1902.

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EDWINLOHMANN, OF GREENV-ILLE, OHIO.

PH OTOG RAPHlCfiEENS =SYSTEM.

SPEGTFICATION forming part of Letters Patent No. 730,937, datedJ'unefl e, 1903;

Application filed November 8, 190 2.}; Serial No. 130,507. iNo model-T'- To all whom it may concern:

Be it known that I, EDWIN 'L'OHMANN, a citizen of the United States, residing at Greenville, in the county of Darke and State of Ohio, have invented a new "and useful-H1119? Purposes, of which the followingis a spiaGifi-f cation.

The object of the present invention is to shorten the relative focal length of photo graphic objectives, while maintaining a satisfactory astigmatic, spheric, and chromatic correction.

The drawing herewith is a longitudinal; cross-section showing an objective embodyg ing the present invention.

The plan of the present invention is essen-% tially that contained in my Letters Patent No.;; 711,985, with the exception that one of the thin positive meniscus lenses there shown is replaced in the present invention by anair-r space Z. This alteration permits the' use of an exceptionally light glass for the biconcave. lens B-in the annexed'drawing, for as the bi-' concave lens B is inolosed on one side by a; glass of lower refractive power and on the otherby an air-space spherical correction is: accomplished at both its curves, and its I'Q-l fractive power may be therefore considerably lower than has hitherto been successfully employed in photographic-lens construction. The relative focal length is thus reduced and greater brilliancy of the image obtained.

The equalization of the 'anastigmatic and spherical-corrections due to the thin-positive meniscus lenses in the before-mentionediLet: ters Patentis maintained inthe present -in-' vention, the air-space Z and the inclosed positive meniscus lens -X"'0f the present invention being of relativelysmall thickness, there. 40

by obtaining the greatest possible equality I {in the axial distances of the points of astigprovementin Lens Systems for Photographic, gmatic and spherical correction in the two pairs of opposing'curves.

The indices given-in the annexed drawing are those-preferably employed. Slight? %;variations are advisable, however','"for'certain ?purposes.

In the present invention the biconvex lens a has the highest refractive power,*(-1:62;)lthe 5o gpositive meniscus lens 0 the nexthighest're ,fractive power, (1.56,) the =biconcave lensfB sfhas the next highest refractivepower,(1,51,) and the positive meniscus lens Xhas the lowest refractive power',:(1:49:-)

Two of the described objectives may be employed to form a photographic doublet.

What I claim is A quadruple-lens system composed of an outer biconvex lens ofhighest refractive 6o Epower, an outer positive meniscus lensof ;next highest refractive power,fan intermedi ":ate biconcave lens of next highest refractive Epower, the outer biconvex and outer positive imeniscus lenses being separated from the in-- stermediate biconcave lens respectively bya fpositive meniscus lens of lowest refractive power and a positive meniscus air-space, sub- -'stantially as shown and'described.

EDWIN 'LOHMANN.

Witnesses:

F, WILSON, OSBORN' WIIJ'SON. 

